1. Field of the Invention
The present invention relates to writable CD and DVD controllers and, in particular, writable CD and DVD controllers for high data-rate writes.
2. Discussion of Related Art
As writable CD and DVD data storage devices become more generally available, the ability to write data to them at high data transmission rates becomes more important. In general, data transmitted from a host device, for example a computer system, is encoded and written onto the optical medium (e.g., writable CD and DVD devices). Data encoding typically involves fetching data from the host device over, for example, an ATAPI protocol bus, and preparing the data for physically writing onto the optical media.
Typically, a controller will include a microcomputer that runs firmware that monitors and controls the various tasks of receiving data from the host device and encoding the data for physically writing to the optical medium. At low transmission rates, and hence low encoding rates, the monitoring and controlling tasks can be easily handled by most microcomputers utilized for the task.
However, at high transmission rates, for example about 48× or higher, the processor speeds are not fast enough for many microcomputers, especially ones that would be typically utilized in CD or DVD controllers, to handle the tasks of monitoring and controlling the data flow as required. Additionally, repetitive firmware tasks can require large firmware codes, and comparatively large amounts of ROM for storing the large firmware codes.
Therefore, there is a need for controllers for writable optical drives that provide for high data transmission rates between the host device and the optical medium. Further, there is a need for controllers that do not require large amounts of ROM for storage of large firmware codes.